"Will it always be like this?" sighed Sun Yuk-hom, more than an hour late for school on the first day of term yesterday after a 4-1/2-hour journey.

The six-year-old rose at 5am at his home in Longhua, Shenzhen, to get ready.

But despite his early start he did not reach his school in Tai Po until almost 9.30am after delays at the heavily congested Man Kam To border crossing.

"I got up so early but now I'm late," he said. "I'll wake up early every day from now."

His story was typical of many of the 16,000 pupils - 3,000 more than last year - who crossed the border to attend Hong Kong schools. Many were late because of chaos at the crossings, which were jammed with buses ferrying the children to school.

Their plight brought a call for government action to seek ways to ease the journey and reduce the stress on the children.

The driver of Sun's bus - which took 29 pupils to Lam Tsuen Public Wong Fook Luen Memorial School - said there were about 20 nanny buses at Man Kam To, three times the number last year.

Ho Man-keung said it took him an hour to pass through the Shenzhen side because only one bus lane was open. "There were never so many students crossing Man Kam To," he said.

"Maybe the border control officers in Shenzhen didn't expect this either and were quite ill-prepared. The Hong Kong side was much better."

It took him 25 minutes to cross the Hong Kong side.

The International Social Service sent out workers to check five of the six crossings and found pupils, parents, carers and school staff had been there since 6am.

Cheung Yuk-ching, director of the organisation's cross-boundary service programme, said it was chaotic at most crossings, with parents separated from their crying children, carers identifying pupils and school staff waiting anxiously.

"Futian and Shenzhen Bay were especially bad," she said. "There was wave after wave of nanny buses." She said the government should seek ways to improve the situation and provide after-school support.

Schools are under pressure from an influx of children born in Hong Kong to mainland parents as well as the children of local families living across the border.

Another pupil at Sun's school, 10-year-old Xu Haiyu, was up at 5.30am and got on a bus that took 33 pupils through the Futian crossing. They were 10 minutes late for the 8.15am assembly.

It then took her three hours to get home to Futian at about 3.30 pm - ending a 10-hour odyssey.

"She looks very tired every day," said Xu's mother, Hong Sixia. "She'll fall asleep immediately after she hits the bed in the evenings at about 8.30pm."

Teacher Chiu Pui-fan said they tended to miss most of the first class - starting at 8.30am - in the first month of every school year because it took time for parents, buses and in-bus caretakers to adapt to the schedule. "Last year, a parent of a cross-border child told me he had nightmares every night," said Chiu. "He didn't get enough sleep and had few friends because he didn't know much Cantonese."

The school has taken about 20 new cross-border children this year in addition to the 60 previously enrolled.

Another bus taking almost 30 pupils to Yan Chai Hospital Choi Hin To Primary School in Tai Po via Futian was also late, and the children missed the school's back-to-school ceremony.

Education minister Eddie Ng Hak-kim, who visited a school in Tai Po, said the cross-border pupils' journey was generally safe and smooth. Undersecretary Kevin Yeung Yun-hung visited three border crossings.